1. Field of the Invention
The present invention relates to a method and apparatus for vectoring and orbiting machine control. More specifically, the invention relates to a method and apparatus for orbiting/vectoring machine control employing a new technique of machine tool control in performing electrical discharge machining (EDM).
2. Description of the Prior Art
In the past, electrical discharge machining had been accomplished by an operator who empirically moved an electrode with respect to a workpiece-carrying work table. In such a conventional approach, machining largely depended on the operator's dexterity, and such techniques were unfit for achieving high precision machining. Such conventional approaches were not effective for enabling complicated work patterns, or at least did not achieve the same in an efficient manner.
As electrical technology became more sophisticated, arrangements were developed wherein the paths of the electrode were controlled by means of electrical control circuitry coupled with servo motor control. Moreover, mechanical and analog signal processing techniques have, for some time, been employed in controlling EDM arrangements. Again, such techniques were relatively simplistic and, as a result, machining had been carried out in a rather unsophisticated, imprecise and inefficient manner. More specifically, EDM control techniques were such that only relatively simple types of machine patterns were able to be carried out.
With the advent of microprocessor-controlled technology, systems and methods were developed for providing a more sophisticated control of the relative movement of the electrode and workpiece in order to machine complex shapes in an efficient manner. One such technique is described in U.S. Pat. No. 4,365,300, assigned to the same assignee as the instant invention. In that patent, a method and apparatus for vector machine control of a tool and a workpiece was described using microprocessor-based technology. Specifically, the system included a dual microprocessor arrangement to control the complete movement of the electrode with respect to a workpiece in both the downward, or z-axis, direction as well as in a transverse polar coordinate plane. In such a system, information was inputted by an operator and such information was displayed on an oscilloscope located on the front panel of the unit. In this patent, one of the microprocessors controlled the manual input and display functions as well as the z-axis control function. The other microprocessor monitored the gap voltage and provided signals to a polar translator for movement of the electrode in the polar coordinate plane via x-axis and y-axis stepping motors. The system of the patent was relatively effective for controlling the basic electrical discharge machine, albeit in a relatively slow and inefficient manner.
Recent advances in the EDM field have resulted in more sophisticated EDM machines which are themselves microprocessor controlled having their own system controller for controlling the z-axis movement and the overall electrical machining. For example, the Eltee Pulsitron Model TRM-21 electrical discharge machine, used in conjunction with an Eltee Pulsitron Model EP300 CP electrical power supply/control system is one such well-known sophisticated EDM system. The electrical discharge machine (TRM-21) includes a work table for supporting the workpiece to be machined and a tool holder, or head, for moving the tool in the z-axis direction under the control of the power supply/control system (EP300CP). The power supply/control system includes a system controller which controls the movement of the tool in the z-axis direction, detects the position of the tool with respect to the workpiece, and controls a gap detector/processor for providing gap voltage across the tool and the workpiece in a manner well known in the art However, such a system does not provide for orbiting and vectoring of the tool relative to the workpiece under control of the system controller to enable complex shapes to be machined in a user-friendly manner. Accordingly, a need has arisen for a vectoring and orbiting control unit, readily adaptable for the sophisticated EDM machine systems and power supply/control systems now on the market such as the TRM-21 EDM machine used in conjunction with the EP300 CP power supply, taking advantage of the relatively sophisticated microprocessor controlled machining capabilities of such units.